1. Field of the Invention
This invention relates to a nacelle that incorporates an air intake at the front of the junction of said nacelle and the mast that supports it and that is called a fairing.
2. Description of the Related Art
An aircraft propulsion system comprises a nacelle in which a power plant, connected by means of a mast to the rest of the aircraft, is arranged in an essentially concentric manner.
The nacelle comprises an inside wall that delimits a pipe with an air intake at the front, a first portion of the incoming air stream, called the primary stream, that passes through the power plant to take part in the combustion process, with the second portion of the air stream, called the secondary stream, being entrained by a fan and flowing into an annular pipe that is delimited by the inside wall of the nacelle and the outside wall of the power plant.
The nacelle also comprises an outside wall with an essentially circular cross-section, which extends from the air intake to the aft exhaust, consisting of the juxtaposition of several elements.
At the front of the junction zone with the nacelle, the mast comprises an aerodynamic surface that is called a fairing and that has as its function to limit the drag at the junction of the nacelle and the mast. Under the aerodynamic loads during flight, the nacelle moves slightly relative to the mast and therefore relative to the fairing, in particular along the longitudinal axis of the nacelle.
The nacelle comprises at least one air system, in particular for ensuring the reheating, the cooling or the ventilation, comprising a circuit that extends from at least one air intake to at least one air exhaust by passing through at least one exchanger or any other device that requires air or that operates with air.
An air system necessarily induces a parasitic drag that originates, for example, from the surface defects linked to the implantation of the intake or the exhaust at the surface that is in contact with the outside air stream or because of the difference between the flows collected and expelled in said air stream.
However, to meet the expectations of the clients, aircraft manufacturers are seeking to improve the aerodynamics of their equipment in order to reduce their operating costs that are strongly linked to the fuel consumption.
This application relates more particularly to an air intake that is also called a scoop.
To limit its impact on aerodynamics, the air intake is to be blocked when there is no need for air. Consequently, certain air intakes comprise a flap that can occupy a first so-called closed position in which the flap blocks the air intake and comes into the extension of the aerodynamic surfaces that surround the air intake, and a second so-called open position in which the flap releases the air intake and allows the passage of air. An actuator, for example a jack, activated by aircraft control means, is used to maneuver the flap.
The flap and the actuator increase the on-board weight and require specific maintenance, which impacts the operating costs.